'There are 18 distinct colours around the compass,' says Hill, who also works for CartoDB.

Pink, for example, represents a river that runs north-south or south-north.

CartoDB is a a cloud based mapping, analysis and visualization engine that lets users build spatial applications for both mobile and the web, and it often used on property websites and new sites to create maps.

Recently, the firm made its technology available for free.

'We realized that charging for map views was actually penalizing you for creating interesting maps,' said Hill.